High-performance microporous titania-silica (Tio(2)-SiO2) nanocomposites with different TiO2 loadings of 0-100 wt% were synthesized using a sol-gel method and evaluated for ultra-deep oxidative desulfurization (ODS) of dibenzothiophene (DBT) using tert-butyl hydroperoxide (TBHP) as oxidant. The prepared catalysts were characterized by the N-2 adsorption-desorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HR-TEM) and ammonia temperature-programmed desorption (NH3-TPD), and the ODS performances were evaluated in a batch reactor. The effects of titanium loading, calcination temperature, and reaction temperature on the catalyst performance were examined. The activity varied significantly with the amount of titanium in the TiO2-SiO2 nanocomposite with a nearly constant turnover frequency (TOF) of about 24.6 h(-1). The TiO2-SiO2 nanocomposite containing 50 wt% titania loading (TS-50) with the highest total acidity was an excellent catalyst capable of removing more than 98% of DBT to less than 10 ppmw, after 20 min. DBT was oxidized to DBT-sulfone (DBTO2), a species with higher polarity that could be subsequently adsorbed on the TS-50 and therefore, the nanocomposite acts as both a catalyst and adsorbent simultaneously. The catalysts could be easily regenerated by calcination at 873 K. An empirical kinetic model was employed to interpret the reaction rate data; the apparent activation energy was 43.8 kJ/mol. Density functional theory (DFT) calculations revealed that DBT and TBHP reactants and DBTO2 product were more strongly adsorbed on (001) surface of beta-cristobalite silica than on (101) surface of anatase titania. The adsorption energy of DBTO2 was larger than DBT on both surfaces. (C) 2015 Elsevier B.V. All rights reserved.